The invention relates to the inspection of motor vehicle engines, and specifically to measuring the vibration of an engine having balancers.
Internal combustion engines typically have at least one piston and connecting rod driving a crankshaft. As the engine operates, reciprocal motion of the piston is translated to rotational movement of the crankshaft. As a result of the reciprocating motion of the piston and connecting rod, engine operation typically generates vibrations of the engine and engine components. The vibration of greatest concern is normally the first-order vibration at a frequency determined by dividing the engine rpm by sixty. Sufficient vibration over a period of time, particularly at certain frequencies, can be uncomfortable for some riders.
Some engine manufacturers have attempted to dampen engine vibration by adding balancers within an engine. If correctly designed and installed, the balancers can counteract a significant portion of the engine vibration, resulting in more comfort to some riders.
If the balancers are slightly misaligned, the balancers can still dampen the engine vibrations, but the balancers will not function to the designed effectiveness. Because the balancers are located within the engine housing, it is difficult to determine whether the balancers are properly aligned. A diagnostic tool other than visual confirmation is desirable.
Prior art methods have sensed and compared first-order vibrations to determine balancer condition, but these methods cannot be used for engines installed in different motorcycle designs, experiencing different motorcycle conditions (e.g., motorcycle tire pressure), or installed on test stands. In other words, the results of these methods vary depending on the engine supporting structure.
The invention provides a method and apparatus for determining the balancer condition of a balanced engine, and is based on the recognition that the ratio of first-order vibration to second-order vibration is relatively independent of the engine supporting structure (e.g., whether the engine is mounted on a test stand or a motorcycle). In the present invention, the ratio of first-order to second-order vibrations of an operating test engine is calculated and compared to the ratio for an engine in which the balancers are properly aligned to determine whether the balancers in the test engine are properly aligned.
The invention described herein solves the problem of determining whether the balancers in an engine are properly aligned by providing a simple diagnostic tool that allows that determination to be made easily and quickly. The method can be used for engines installed in different motorcycle designs, experiencing different motorcycle conditions (e.g., motorcycle tire pressure), or installed on test stands. As a result, an engine can be inspected for proper balancing before the engine is sold to and operated by a consumer.
Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims, and drawings.